Realization of an all-dielectric zero-index optical metamaterial

TL;DR

This paper demonstrates an all-dielectric zero-index optical metamaterial using silicon rods, enabling low-loss, directional light manipulation at optical frequencies, which overcomes previous metallic loss issues.

Contribution

The authors experimentally realize a dielectric zero-index metamaterial at optical frequencies, avoiding metallic losses and enabling new optical device functionalities.

Findings

Achieved impedance-matched zero-index behavior with silicon rods

Demonstrated angular selectivity of transmission

Observed directive emission from embedded quantum dots

Abstract

Metamaterials offer unprecedented flexibility for manipulating the optical properties of matter, including the ability to access negative index, ultra-high index and chiral optical properties. Recently, metamaterials with near-zero refractive index have drawn much attention. Light inside such materials experiences no spatial phase change and extremely large phase velocity, properties that can be applied for realizing directional emission, tunneling waveguides, large area single mode devices, and electromagnetic cloaks. However, at optical frequencies previously demonstrated zero- or negative-refractive index metamaterials require the use of metallic inclusions, leading to large ohmic loss, a serious impediment to device applications. Here, we experimentally demonstrate an impedance matched zero-index metamaterial at optical frequencies based on purely dielectric constituents. Formed from stacked silicon rod unit cells, the metamaterial possesses a nearly isotropic low-index response leading to angular selectivity of transmission and directive emission from quantum dots placed within the material.